Multi-speed transmission

ABSTRACT

A transmission is provided having an input member, an output member, at least four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices include clutches and a brake actuatable in combinations of four to establish a plurality of forward gear ratios and at least one reverse gear ratio.

FIELD

The invention relates generally to a multiple speed transmission, andmore particularly, to a transmission having a plurality of speeds, fourplanetary gear sets and a plurality of torque transmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches, planetary gear arrangements and fixed interconnections toachieve a plurality of gear ratios. The number and physical arrangementof the planetary gear sets, generally, are dictated by packaging, costand desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness, and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member, atleast four planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices may be, for example, clutches and a brake.

The clutches and brake can be of any type including but not limited to afiction clutch, a friction band, a one way clutch, a selectable one wayclutch, a dog clutch, a synchronizer and similar devices. Furthermore,any node can use a single device or a combination of these devices e.g.the brake may be configured as a dog clutch and a one way clutchcombination or a one way clutch and friction clutch combination.Similarly, several other combinations are possible.

In another embodiment of the present invention, the transmissionincludes: first, second, third and fourth planetary gear sets eachhaving a sun gear, a carrier member and a ring gear, and the inputmember is continuously connected for common rotation with the carriermember of the second planetary gear set, and the output member iscontinuously connected for common rotation with the carrier member ofthe fourth planetary gear set.

In yet another embodiment of the present invention, the transmissionincludes a first interconnecting member continuously interconnecting thering gear of the first planetary gear set with the ring gear of thefourth planetary gear set.

In yet another embodiment of the present invention, the transmissionincludes a second interconnecting member continuously interconnectingthe sun gear of the first planetary gear set with the sun gear of thesecond planetary gear set.

In yet another embodiment of the present invention, the transmissionincludes a third interconnecting member continuously interconnecting thering gear of the second planetary gear set with the sun gear of thethird planetary gear set.

In yet another embodiment of the present invention, the transmissionincludes a fourth interconnecting member continuously interconnectingthe ring gear of the third planetary gear set with the sun gear of thefourth planetary gear set.

In still another embodiment of the present invention, the transmissionincludes a first torque transmitting mechanism that is selectivelyengageable to interconnect the ring gear of the third planetary gear setand the sun gear of the fourth planetary gear set with the carriermember of the second planetary gear set and the input member.

In still another embodiment of the present invention, the transmissionincludes a second torque transmitting mechanism that is selectivelyengageable to interconnect the carrier member of the first planetarygear set with the ring gear of the second planetary gear set and the sungear of the third planetary gear set.

In still another embodiment of the present invention, the transmissionincludes a third torque transmitting mechanism that is selectivelyengageable to interconnect the ring gear of the second planetary gearset and the sun gear of the third planetary gear set with a commonstructural member.

In still another embodiment of the present invention, the transmissionincludes a fourth torque transmitting mechanism that is selectivelyengageable to interconnect the carrier member of the third planetarygear set with the common structural member.

In still another embodiment of the present invention, the transmissionincludes a fifth torque transmitting mechanism that is selectivelyengageable to interconnect the ring gear of the first planetary gear setand the ring gear of the fourth planetary gear set with the commonstructural member.

In still another embodiment of the present invention, the transmissionincludes a sixth torque transmitting mechanism that is selectivelyengageable to interconnect the sun gear of the first planetary gear setand the sun gear of the second planetary gear set with the stationarymember.

In still another embodiment of the present invention, the transmissionincludes a seventh torque transmitting mechanism that is selectivelyengageable to interconnect the carrier member of the first planetarygear set with the stationary member.

In yet another embodiment of the present invention, the torquetransmitting mechanisms are selectively engageable in combinations of atleast four to establish a plurality of forward speed ratios and at leastone reverse speed ratio between the input member and the output member.

Further features, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of a transmission accordingto the principles of present invention;

FIG. 2 is a diagrammatic illustration of a variation of the transmissionof FIG. 1 according to the principles of the present invention; and

FIG. 3 is a truth table presenting an example of a state of engagementof various torque transmitting elements to produce multiple forward andat least one reverse speed or gear ratios of the transmissionsillustrated in FIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that the embodiments of themulti-speed automatic transmission of the present invention have anarrangement of permanent mechanical connections between the elements ofthe four planetary gear sets. As used herein, coupling orinterconnection refers to a direct, continuous, and permanent couplingor interconnection, for example by a rigid member or shaft, betweenelements. Selective coupling or interconnection, on the other hand,refers to a selective coupling by a clutch or brake, where the clutch orbrake can be engaged and disengaged, such that when engaged, theselectively coupled or interconnected elements rotate together, but whendisengaged, the selectively coupled or interconnected elements are freeto rotate independently.

In an embodiment, a first component or element of the first planetarygear set is permanently coupled to a third component or element of thesecond planetary gear set. A second component or element of the firstplanetary gear set is permanently coupled to a third component orelement of the fourth planetary gear set. A first component or elementof the second planetary gear set is permanently coupled to a firstcomponent or element of the third planetary gear set. A third componentor element of the third planetary gear set is permanently coupled to afirst component or element of the fourth planetary gear set.

Referring now to FIG. 1, an embodiment of a multi-speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear set are each represented by a node. Therefore, a single levercontains three nodes: one for the sun gear, one for the planet gearcarrier, and one for the ring gear. The relative length between thenodes of each lever can be used to represent the ring-to-sun ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve an appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines, and torque transmitting devices such as clutchesand brakes are presented as interleaved fingers. Further explanation ofthe format, purpose and use of lever diagrams can be found in SAE Paper810102, “The Lever Analogy: A New Tool in Transmission Analysis” byBenford and Leising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14, a second planetary gear set 16, a third planetarygear set 18, a fourth planetary gear set 20, and an output shaft ormember 22. In the lever diagram of FIG. 1, the first planetary gear set14 has three nodes: a first node 14A, a second node 14B, and a thirdnode 14C. The second planetary gear set 16 has three nodes: a first node16A, a second node 16B and a third node 16C. The third planetary gearset 18 has three nodes: a first node 18A, a second node 18B and a thirdnode 18C. The fourth planetary gear set 20 has three nodes: a first node20A, a second node 20B and a third node 20C. The input member 12 iscontinuously coupled to the second node 16B of the second planetary gearset 16. The output member 22 is continuously coupled to the second node20B of the fourth planetary gear set 20.

The first node 14A of the first planetary gear set 14 is coupled to thethird node 16C of the second planetary gear set 16. The second node 14Bof the first planetary gear set 14 is coupled to the third node 20C ofthe fourth planetary gear set 20. The first node 16A of the secondplanetary gear set 16 is coupled to first node 18A of the thirdplanetary gear set 18. The third node 18C of the third planetary gearset 18 is coupled to the first node 20A of the fourth planetary gear set20.

Transmission 10 has a plurality of torque transmitting mechanisms, suchas clutches and brakes, which transfer torque from one node or elementof the planetary gear sets to another. Moreover, transmission 10includes a common node J. Common node J is a structural member thatinterconnects a number of the torque transmitting mechanisms, asdescribed hereinafter.

For example, a first clutch 24 selectively connects the second node 16Bof the second planetary gear set 16 and the input member 12 with thethird node 18C of the third planetary gear set 18 and the first node 20Aof the fourth planetary gear set 20. A second clutch 26 selectivelyconnects the third node 14C of the first planetary gear set 14 with thefirst node 16A of the second planetary gear set 16 and the first node18A of the third planetary gear set 18. A third clutch 28 selectivelyconnects the first node 16A of the second planetary gear set 16 and thefirst node 18A of the third planetary gear set 18 with the common nodeJ. A fourth clutch 30 selectively connects the second node 18B of thethird planetary gear set 18 with the common node J. A fifth clutch 32selectively connects the second node 14B of the first planetary gear set14 and the third node 20C of the fourth planetary gear set 20 with thecommon node J. A first brake 34 selectively connects the first node 14Aof the first planetary gear set 14 and the third node 16C of the secondplanetary gear set 16 with the stationary member or transmission housing50. A second brake 36 selectively connects the third node 14C of thefirst planetary gear set 14 with the stationary member or transmissionhousing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofan embodiment of the multi-speed transmission 10 according to one formof the present invention. In FIG. 2, the numbering from the leverdiagram of FIG. 1 is carried over. The clutches and couplings arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers.

For example, the first planetary gear set 14 includes a sun gear member14A, a ring gear member 14B and a planet gear carrier member 14C thatrotatably supports a first set of planet gears 14D (only one of which isshown) and a second set of planet gears 14E (only one of which isshown). The sun gear member 14A is connected for common rotation with afirst shaft or interconnecting member 42 and a second shaft orinterconnecting member 44. The ring gear member 14B is connected forcommon rotation with a third shaft or interconnecting member 46. Theplanet carrier member 14C is connected for common rotation with fourthshaft or interconnecting member 48 and a fifth shaft or interconnectingmember 52. The first set of planet gears 14D are each configured tointermesh with both the sun gear member 14A and the second set of planetgears 14E. The second set of planet gears 14E are each configured tointermesh with both the ring gear member 14B and the first set of planetgears 14D.

The second planetary gear set 16 includes a sun gear member 16C, a ringgear member 16A and a planet gear carrier member 16B that rotatablysupports a set of planetary gears 16D (only one of each is shown). Thesun gear member 16C is connected for common rotation with the secondshaft or interconnecting member 44. The ring gear member 16A isconnected for common rotation with a sixth shaft or interconnectingmember 54 and the seventh shaft or interconnecting member 56. The planetcarrier member 16B is connected for common rotation with the input shaftor member 12. The planet gears 16D are each configured to intermesh withboth the ring gear member 16A and the sun gear member 16C.

The third planetary gear set 18 includes a sun gear member 18A, a ringgear member 18C and a planet gear carrier member 18B that rotatablysupports a set of planet gears 18D (only one of which is shown). The sungear member 18A is connected for common rotation with the seventh shaftor interconnecting member 56. The ring gear member 18C is connected forcommon rotation with an eighth shaft or interconnecting member 58. Theplanet carrier member 18B is connected for common rotation with a ninthshaft or interconnecting member 60. The planet gears 18D are eachconfigured to intermesh with both the sun gear member 18A and the ringgear member 18C.

The fourth planetary gear set 20 includes a sun gear member 20A, a ringgear member 20C and a planet gear carrier member 20B that rotatablysupports a set of planet gears 20D (only one of which is shown). The sungear member 20A is connected for common rotation with the eighth shaftor interconnecting member 58. The ring gear member 20C is connected forcommon rotation with the third shaft or interconnecting member 46. Theplanetary gear carrier member 20B is connected for common rotation withthe output shaft or member 22. The planet gears 20D are each configuredto intermesh with both the sun gear member 20A and the ring gear member20C.

The input shaft or member 12 is continuously connected to an inputsource, such as an engine (not shown) or a turbine of a torque converteror a starting clutch or the like (not shown). The output shaft or member22 is continuously connected with another output such as the final driveunit or transfer case (not shown).

The torque-transmitting mechanisms, including the first, second, third,fourth and fifth clutches 24, 26, 28, 30, 32 and the brakes 34 and 36allow for selective interconnection of the shafts or interconnectingmembers 42, 44, 46, 48, 52, 54, 56, 58 and 60 of the planetary gear sets14, 16, 18, 20 and the housing 50.

For example, the first clutch 24 is selectively engageable to connectthe eighth shaft or interconnecting member 58 for common rotation withthe input member 12. The second clutch 26 is selectively engageable toconnect the fifth shaft or interconnecting member 52 for common rotationwith the sixth shaft or interconnecting member 54. The third clutch 28is selectively engageable to connect the seventh shaft orinterconnecting member 56 with the common member or hub J. The fourthclutch 30 is selectively engageable to connect the ninth shaft orinterconnecting member 60 with the common member or hub J. The fifthclutch 32 is selectively engageable to connect the third shaft orinterconnecting member 46 with the common member or hub J. The firstbrake 34 is selectively engageable to connect the first shaft orinterconnecting member 42 with the stationary element or thetransmission housing 50 in order to restrict the sun gears 14A and 16Cfrom rotating relative to the transmission housing 50. The second brake36 is selectively engageable to connect the fourth shaft orinterconnecting member 48 with the stationary element or thetransmission housing 50 in order to restrict the carrier member 14C fromrotating relative to the transmission housing 50. In turn, thecomponents of the planetary gear sets connected to each of theconnecting members are also connected or restricted accordingly.

Referring now to FIGS. 1, 2 and 3, the operation of the multi-speedtransmission 10 will be described. It will be appreciated thattransmission 10 is capable of transmitting torque from the input shaftor member 12 to the output shaft or member 22 in multiple forward speedtorque ratios and at least one reverse speed or torque ratio. Eachforward and reverse speed or torque ratio is attained by engagement ofone or more of the torque-transmitting mechanisms (i.e. first clutch 24,second clutch 26, third clutch 28, fourth clutch 30, fifth clutch 32,first brake 34 and second brake 36), as will be explained below.

FIG. 3 is a truth table presenting the various combinations oftorque-transmitting mechanisms that are activated or engaged to achievethe various gear states. An “X” in the box means that the particularclutch or brake is engaged to achieve the desired gear state. Actualnumerical gear ratios of the various gear states are also presentedalthough it should be appreciated that these numerical values areexemplary only and that they may be adjusted over significant ranges toaccommodate various applications and operational criteria of thetransmission 10. Of course, other gear ratios are achievable dependingon the gear diameter, gear teeth count and gear configuration selected.

For example, a reverse gear is established by engaging or activating thefourth clutch 30, the fifth clutch 32, the first brake 34 and the secondbrake 36. The fourth clutch 30 connects the ninth shaft orinterconnecting member 60 with the common member or hub J. The fifthclutch 32 connects the third shaft or interconnecting member 46 with thecommon member or hub J. The first brake 34 connects the sun gears 14Aand 16C with the stationary element or the transmission housing 50 inorder to restrict the sun gears 14A and 16C from rotating relative tothe transmission housing 50. The second brake 36 connects the carriermember 14C with the stationary element or the transmission housing 50 inorder to restrict the carrier member 14C from rotating relative to thetransmission housing 50. Likewise, the sixteen forward ratios areachieved through different combinations of clutch and brake engagement,as shown in FIG. 3, by way of example.

It will be appreciated that the foregoing explanation of operation andgear states of the multi-speed embodiment of transmission 10 assumes,first of all, that all the clutches not specifically referenced in agiven gear state are inactive or disengaged and, second of all, thatduring gear shifts, i.e., changes of gear state, between at leastadjacent gear states, a clutch engaged or activated in both gear stateswill remain engaged or activated. Further, the operation andestablishment of various gear ratios of transmission 10 are for exampleprovided by the engagement of the torque transmitting elements, as shownin FIG. 3. For example, additional combinations of clutch and brakeengagements to establish first gear, eighth gear, tenth gear and twelfthgear are also presented. Advantageously, some of the additionalcombinations of clutch and brake engagements only require a combinationof three clutch and brake engagements instead of four clutch and brakeengagements to establish the particular gear ratio.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members; four interconnecting members continuouslyinterconnecting a member of the first, second, third and fourthplanetary gear sets with another member of the first, second, third andfourth planetary gear sets; and seven torque transmitting mechanismswherein five of the seven torque transmitting mechanisms are eachselectively engageable to interconnect at least one of the first, secondand third members with at least one other of the first, second, thirdmembers and a common structural member and wherein two of the seventorque transmitting mechanisms are each selectively engageable tointerconnect at least one of the first, second and third members with astationary member, and wherein the seven torque transmitting mechanismsare selectively engageable in combinations of at least four to establisha plurality of forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.
 2. The transmission ofclaim 1 wherein the four interconnecting members further comprises afirst interconnecting member continuously interconnecting a secondmember of the first planetary gear set with a third member of the fourthplanetary gear set, a second interconnecting member continuouslyinterconnecting a first member of the first planetary gear set with athird member of the second planetary gear set, a third interconnectingmember continuously interconnecting a first member of the secondplanetary gear set with a first member of the third planetary gear setand a fourth interconnecting member continuously interconnecting a thirdmember of the third planetary gear set with a first member of the fourthplanetary gear set.
 3. The transmission of claim 1 wherein a first ofthe seven torque transmitting mechanisms is selectively engageable tointerconnect the third member of the third planetary gear set and thefirst member of the fourth planetary gear set with the second member ofthe second planetary gear set and the input member.
 4. The transmissionof claim 3 wherein a second of the seven torque transmitting mechanismsis selectively engageable to interconnect the third member of the firstplanetary gear set with the first member of the second planetary gearset and the first member of the third planetary gear set.
 5. Thetransmission of claim 4 wherein a third of the seven torque transmittingmechanisms is selectively engageable to interconnect the first member ofthe second planetary gear set and the first member of the thirdplanetary gear set with the common structural member.
 6. Thetransmission of claim 5 wherein a fourth of the seven torquetransmitting mechanisms is selectively engageable to interconnect thesecond member of the third planetary gear set with the common structuralmember.
 7. The transmission of claim 6 wherein a fifth of the seventorque transmitting mechanisms is selectively engageable to interconnectthe second member of the first planetary gear set and the third memberof the fourth planetary gear set with the common structural member. 8.The transmission of claim 7 wherein a sixth of the seven torquetransmitting mechanisms is selectively engageable to interconnect thefirst member of the first planetary gear set and the third member of thesecond planetary gear set with the stationary member.
 9. Thetransmission of claim 8 wherein a seventh of the seven torquetransmitting mechanisms is selectively engageable to interconnect thethird member of the first planetary gear set with the stationary member.10. The transmission of claim 1 wherein the input member is continuouslyconnected for common rotation with the second member of the secondplanetary gear set and the output member is continuously connected forcommon rotation with the second member of the fourth planetary gear set.11. The transmission of claim 1 wherein the first member of the firstplanetary gear set, the third member of the second planetary gear set,the first member of the third planetary gear set and the first member ofthe fourth planetary gear set are sun gears, the second members of thesecond, third and fourth planetary gear sets and the third member of thefirst planetary gear set are carrier members and the second member ofthe first planetary gear set, the first member of the second planetarygear set, the third member of the third planetary gear set and the thirdmember of the fourth planetary gear set are ring gears.
 12. Atransmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members; a first interconnecting member continuouslyinterconnecting a second member of the first planetary gear set with athird member of the fourth planetary gear set; a second interconnectingmember continuously interconnecting a first member of the firstplanetary gear set with a third member of the second planetary gear set;a third interconnecting member continuously interconnecting a firstmember of the second planetary gear set with a first member of the thirdplanetary gear set; a fourth interconnecting member continuouslyinterconnecting a third member of the third planetary gear set with afirst member of the fourth planetary gear set; and seven torquetransmitting mechanisms each selectively engageable to interconnect atleast one of the first, second, and third members with at least oneother of the first, second, third members and a common structural memberand the stationary member, and wherein the seven torque transmittingmechanisms are selectively engageable in combinations of at least fourto establish a plurality of forward speed ratios and at least onereverse speed ratio between the input member and the output member. 13.The transmission of claim 12 wherein a first of the seven torquetransmitting mechanisms is selectively engageable to interconnect thethird member of the third planetary gear set and the first member of thefourth planetary gear set with the second member of the second planetarygear set input member.
 14. The transmission of claim 13 wherein a secondof the seven torque transmitting mechanisms is selectively engageable tointerconnect the third member of the first planetary gear set with thefirst member of the second planetary gear set and the first member ofthe third planetary gear set.
 15. The transmission of claim 14 wherein athird of the seven torque transmitting mechanisms is selectivelyengageable to interconnect the first member of the second planetary gearset and the first member of the third planetary gear set with the commonstructural member.
 16. The transmission of claim 15 wherein a fourth ofthe seven torque transmitting mechanisms is selectively engageable tointerconnect the second member of the third planetary gear set with thecommon structural member.
 17. The transmission of claim 16 wherein afifth of the seven torque transmitting mechanisms is selectivelyengageable to interconnect the second member of the first planetary gearset and the third member of the fourth planetary gear set with thecommon structural member.
 18. The transmission of claim 17 wherein asixth of the seven torque transmitting mechanisms is selectivelyengageable to interconnect the first member of the first planetary gearset and the third member of the second planetary gear set with thestationary member.
 19. The transmission of claim 18 wherein a seventh ofthe seven torque transmitting mechanisms is selectively engageable tointerconnect the third member of the first planetary gear set with thestationary member.
 20. The transmission of claim 12 wherein the inputmember is continuously connected for common rotation with the secondmember of the second planetary gear set and the output member iscontinuously connected for common rotation with the second member of thefourth planetary gear set.
 21. The transmission of claim 12 wherein thefirst member of the first planetary gear set, the third member of thesecond planetary gear set, the first member of the third planetary gearset and the first member of the fourth planetary gear set are sun gears,the second members of the second, third and fourth planetary gear setsand the third member of the first planetary gear set are carrier membersand the second member of the first planetary gear set, the first memberof the second planetary gear set, the third member of the thirdplanetary gear set and the third member of the fourth planetary gear setare ring gears.
 22. A transmission comprising: an input member; anoutput member; first, second, third and fourth planetary gear sets eachhaving a sun gear, a carrier member and a ring gear, wherein the inputmember is continuously connected for common rotation with the carriermember of the second planetary gear set and the output member iscontinuously connected for common rotation with the carrier member ofthe fourth planetary gear set; a first interconnecting membercontinuously interconnecting the ring gear of the first planetary gearset with the ring gear of the fourth planetary gear set; a secondinterconnecting member continuously interconnecting the sun gear of thefirst planetary gear set with the sun gear of the second planetary gearset; a third interconnecting member continuously interconnecting thering gear of the second planetary gear set with the sun gear of thethird planetary gear set; a fourth interconnecting member continuouslyinterconnecting the ring gear of the third planetary gear set with thesun gear of the fourth planetary gear set; a first torque transmittingmechanism selectively engageable to interconnect the ring gear of thethird planetary gear set and the sun gear of the fourth planetary gearset with the carrier member of the second planetary gear set and theinput member; a second torque transmitting mechanism selectivelyengageable to interconnect the carrier member of the first planetarygear set with the ring gear of the second planetary gear set and the sungear of the third planetary gear set; a third torque transmittingmechanism selectively engageable to interconnect the ring gear of thesecond planetary gear set and the sun gear of the third planetary gearset with a common structural member; a fourth torque transmittingmechanism selectively engageable to interconnect the carrier member ofthe third planetary gear set with the common structural member; a fifthtorque transmitting mechanism selectively engageable to interconnect thering gear of the first planetary gear set and the ring gear of thefourth planetary gear set with the common structural member; a sixthtorque transmitting mechanism selectively engageable to interconnect thesun gear of the first planetary gear set and the sun gear of the secondplanetary gear set with the stationary member; and a seventh torquetransmitting mechanism selectively engageable to interconnect thecarrier member of the first planetary gear set with the stationarymember, and wherein the torque transmitting mechanisms are selectivelyengageable in combinations of at least four to establish a plurality offorward speed ratios and at least one reverse speed ratio between theinput member and the output member.